Crankcase ventilation arrangement



June 14, 1966 w. H. KOLBE ET AL CRANKCASE VENTILATION ARRANGEMENT Filed May 25, 1964 the creation of pressure in the crankcase.

United States Patent 3,255,743 CRANKCASE VENTILATEON ARRANGEMENT William H. Kolbe, Birmingham, and Arthur I. S. Hyde,

Rochester, Mich, assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed May 25, 1964, Ser. No. 369,817 Claims. (Cl. 123-419) This invention relates to crankcase ventilation systems for internal combustion engines and in particular to a closed system adapted to permit the controlled flow of crankcase vapors from the engine crankcase to the inlet manifold and having provision for the admission of a restricted flow of fresh ventilating air to the crankcase while including one-way valve means to prevent the escape of crankcase vapors to atmosphere.

It is known to ventilate the crankcase of an internal combustion engine by passing crankcase vapors into the engine inlet manifold and to control the flow of such vapors by means of a crankcase depression regulator which regulates the flow so as to normally maintain a relatively constant predetermined vacuum in the engine crankcase.

When provision is made in such a system for the introduction of fresh air into the engine crankcase, it is necessary to restrict the inlet opening in order to permit the desired crankcase vacuum to be obtained. A common provision is the placement in the crankcase fresh air inlet of an orifice which is sized in relation to the maximum controlled vacuum to be maintained in the crankcase so as to transmit the desired flow of ventilating air under normal conditions.

In the operation of systems of the type described, it has been found that under conditions of heavy load and near wide open throttle, blowby of gases past the piston rings and into the crankcase is at a maximum whereas inlet manifold vacuum is at a minimum and a condition may result wherein manifold vacuum is insutficient to prevent As a consequence, it is possible under these limited circumstances that small amounts of crankcase vapors could escape through the fresh air inlet means, adding in minute degree to the pollution of the atmosphere.

In order to provide a closed system in which the ex haust of crankcase vapors to atmosphere is prevented under all engine operating conditions, it is a feature of the instant invention that it provides for the incorporation into the fresh air inlet means of one-way valve means which close in response to a very small crankcase pressure to prevent the flow of crankcase vapors through the inlet means to atmosphere.

An additional feature of the invention is that the oneway valve means includes a restrictive passage for limiting the flow of fresh air to the crankcase as is required for proper operation of the crankcase depression regulator.

A further feature of this invention is that the one-way valve means may be' contained within a breather cap secured to the crankcase oil filler opening.

Yet another feature of the invention is that the one-way valve means include a plate having a plurality of openings therethrough, perforated stop means secured to the plate and having a portion spaced from the plate adjacent the openings and a flexible flat reed secured between the plate and the stop means and adapted to cover the-openings so asto prevent flow therethrough in a direction from the engine crankcase and movable away from the openings in response to How therethrough in a direction toward the engine crankcase.

Still another feature of the invention is that the perforated stop means are adapted to be engaged by the reed so as to maintain a desired maximum clearance between 3,255,743 Patented June 14, 1966 the reed and the plate adjacent the openings to provide a controlled restriction for inlet air fiow.

A still further feature of the invention is that the stop means may be deformed toward or away from the plate so as to provide for adjustment of the desired maximum clearance between the reed and the plate thereby providing an adjustable air flow restriction.

Other novel features of the invention will be apparent from the following specification and drawings in which:

FIGURE 1 is an end elevational view of an interval combustion engine embodying the invention;

FIGURE 2 is an enlarged view of a portion of FIG- URE 1 including a breather cap partially broken away to show its incorporation of one-way valve means according to the invention;

FIGURE 3 is a cross-sectional view of the breather cap of FIGURE 2 taken along the lines 33 of FIGURE 2; and

FIGURE 4- is an exploded perspective view showing the separate elements making up one-way valve means according to the invention.

Referring now to the drawings, an engine generally indicated by numeral incldues a crankcase l2 and an induction system including an inlet manifold 14 down stream of the usual carburetor 16 having a throttle valve 13. Rocker covers 20 and 22 are provided, partially defining compartments in communication with the crankcase 12. A crankcase depression regulator 24 is mounted in an opening in rocker cover 20 and is connected by a conduit 26 to the inlet manifold 14 thus providing a flow path for crankcase vapors extending from crankcase 12 through rocker cover 20, regulator 24 and conduit 26 to the inlet manifold 14. Crankcase regulator 24 may be of any suitable type which regulates the flow of vapors so as to maintain a controlled maximum vacuum within the engine crankcase. An example of such a regulator is that disclosed in FIGURE 1 of US. Patent No. 2,080,588, Whittington.

Instead of being connected directly to the inlet manifold 14, conduit 26 could equally well be connected to any portion of the induction system downstream of the throttle valve 18 in which vacuum substantially equal to that occurring in the inlet manifold is present. Therefore, as subsequently used in the specification and claims, references to the inlet manifold are intended to be broadly construed as referring to any such portion of the induction system.

Rocker cover 22 is provided with an oil filler opening 28 which is closed by a breather cap generally indicated by numeral 30. The closure provides an airtight seal to prevent the entrance of air except through the breather cap 30 as subsequently described. Breather cap 30 thus constitutes the only path for the entrance of fresh air into crankcase 12 and it should be understood that it could be located so as to communicate with any suitable portion of the crankcase and need not necessarily be mounted on rocker cover 22 as shown in the drawings.

As shown in FIGURES 2 and 3, breather cap 30 com prises a sheet metal outer cover 32 having a lower portion 34 including air holes 36. A perforated cylindrical sleeve 38 is retained by lower portion 34 and is filled with filter material 40 which may be of any suitable type. Sealingly secured at the lower end of sleeve 38 and retaining filter material 40 is a valve plate 42 which comprises a portion of the novel one-way valve means of the instant invention and which is best shown in FIGURE 4. A plurality of openings 44 are provided in plate 42 for the passage of air therethrough.

On the outlet side of plate 42, a flexible elastomeric reed 46 and a sheet metal stop member 48 are secured at one of their respective ends by means such as rivet 50. The other end of reed 46 extends over and, when lying flat against plate 42, is adapted to close openings 44 preventing the passage of air therethrough. The unfixed end of stop member 48 is preferably perforated as at 52 for a purpose to be subsequently described and is offset a predetermined amount so as to allow the movement of the free end of reed 46 away from plate 42 to create a desired clearance therebetween, thereby allowing the passage of air through openings 44 and through the clearance between reed 46 and plate 42. The offset portion of stop member 48 is adapted to be deformed toward or away from plate 42 as indicated by phantom lines in order to adjust as desired themaximum clearance permitted and change the air flow restriction offered thereby.

The lower portion 34 of breather cap 30 includes means for sealingly retaining the cap in the engine oil tiller opening and also includes one or more openings 54 permitting communication between the interior of the breather cap and the engine crankcase.

During normal operation of the engine crankcase, vapors are drawn through crankcase depression regulator 24 and conduit 26 into the inlet mainfold 14 due to the manifold vacuum existing therein. Crankcase depression regulator 24 operates to limit the vacuum created in crankcase 12 to a predetermined maximum value.

The crankcase vacuum in turn causes the drawing of fresh air into the crankcase through breather cap 30. The air flow follows a path through openings 36 and perforated s'leeve 38, thence through filter material 40 and openings 44 forcing reed 46 against the offset portion of stop 48 and passing through the clearance between the reed and plate 42. The air then passes through openings 54 and continues on into the engine crankcase. The adjustable clearance between reed 46 and plate 42 creates a restriction limiting the inflow of ventilating air in relation to the crankcase vacuum maintained.

Under conditions of heavy load and near wide open throttle, blowby of combustion gases into the engine crankcase is at its peak while the inlet manifold vacuum becomes extremely low and, consequently, a condition may result in which the crankcase is slightly pressurized. In such a case, perforations 52 in stop member 48 allow an extremely small crankcase pressure to act against flexible reed 46, causing it to move away from stop member 48 and against plate 42, closing openings 44 and preventing the escape of crankcase vapors to atmosphere through breather cap 30. Consequently, the crankcase vapors can pass only into the inlet manifold through crankcase depression regulator 24 which, under such condition, is at its fully open position allowing the free passage of crankcase vapors therethrough.

Thus, it is seen that a crankcase ventilation system is obtained which provides for the ventilation of the crankcase with a limited quantity of fresh air while regulating crankcase vacuum to a predetermined maximum value and having novel valve means to prevent the escape of crankcase vapors to atmosphere under all conditions of engine operation. Such a system is obtained using inexpensive components easily adapted for installation on existing engines.

It should be understood that the fresh air inlet means need not necessarily take the form of a removable breather cap but could be fixed means connected to any suitable portion of the engine in communication with the crankcase 12. Furthermore, it is Within the contemplation of the broadest aspects of the instant invention that oneway valve means other than the type disclosed could be utilized in the crankcase ventilation system. The only requirements being that such valve means operate to prevent the escape of crankcase vapors to atmosphere under crankcase pressure conditions while during normal operation, when a vacuum exists in the crankcase, a restricted path for the passage of ventilating air into the crankcase is provided.

What is claimed is:

1. In a breather cap adapted to be secured to opening 4 means communicating with the crankcase of an internal combustion engine, such breather cap including passage means for permitting the flow of fresh air into such crankcase, one-way valve means in said passage means and adapted to control the flow of fluids through said breather cap and comprising:

a plate having at least One opening provided for fluid flow therethrough;

a flexible fiat reed secured at one end to said plate and adapted to cover each said opening so as to prevent flow therethrough from such crankcase and movable away from each said opening in response to flow therethrough into such crankcase;

and stop means secured at one end to said plate and having a portion spaced from said plate adjacent each said opening and adapted to be engaged by said reed whereby to maintain a desired maximum clearance between said reed and said plate adjacent each said opening to provide a predetermined resistance to fluid flow therethrough into such crankcase, said stop means being deformable whereby said desired maximum clearance may be adjusted to vary said predetermined resistance to fluid flow.

2. One-way valve means adapted to control the flow of low pressure fluids and comprising:

a plate having at least one opening therethrough;

a flexible fiat reed secured at one end to said plate and adapted to cover each said opening so as to prevent flow therethrough in one direction and movable away from each said opening in response to flow therethrough in the other direction;

and stop means secured at one end to said plate and having a portion spaced from said plate adjacent each said opening and adapted to be engaged by said reed whereby to maintain a desired maximum clearance between said reed and said plate adjacent each said opening to provide a predetermined resistance to fluid flow through each said opening in said other direction, said stop means being deformable whereby said desired maximum clearance may be adjusted to vary said predetermined resistance to fluid flow.

3. One-way valve means adapted to control the flow of low pressure fluids and comprising:

a plate having a plurality of openings therethrough;

a flexible fiat reed secured at one end to said plate and adapted to cover said openings so as to prevent flow therethrough in one direction and movable away from said openings in response to flow therethrough in the other direction;

and perforated stop means secured at one end to said plate and having a portion spaced from said plate adjacent said openings and adapted to be engaged by said reed whereby to maintain a desired maximum clearance between said reed and said plate adjacent said openings, said stop means being deformable whereby said desired maximum clearance may be adjusted.

4. In an internal combustion engine of the type having a crankcase and an inlet manifold, crankcase ventilation means comprising:

conduit means connecting such crankcase with such inlet manifold;

21 crankcase depression regulator in said conduit means and regulating the fiow of crankcase vapors from such crankcase to such inlet manifold;

fresh air inlet means communicating such crankcase with atmosphere;

and one-way valve means in said fresh air inlet means,

said valve means being operative to prevent the escape of crankcase vapors to atmosphere and to limit the flow of fresh air into such crankcase through said inlet means, said one-way valve means comprising:

passage means providing for the flow of ventilating air therethrough;

a flexible reed secured to said passage means and movable into and out of a position blocking the flow of air through said passage means;

and stop means spaced from said passage means and adapted to be engaged by said reed when out of such locking position to maintain a desired maximum clearance between said reed and said passage means so as to provide a predetermined resistance to air flow therethrough into such crankcase.

5. The arrangement of claim 4 wherein said stop means is deformable whereby said desired maximum clearance may be adjusted to vary said predetermined resistance to air flow.

References Cited by the Examiner UNITED STATES PATENTS 4/ 1904 Mansfield 137-525 .3

8/1964 Barr 123-119 12/1964 Risse 123-119 3/1965 Lentz 1231 19 6/1965 Humphreys 123119 FOREIGN PATENTS 7/ 1944 Great Britain.

KARL I. ALBRECHT, Primary Examiner. 

4. IN AN INTERNAL COMBUSTION ENGINE OF THE TYPE HAVING A CRANKCASE AND AN INLET MANIFOLD, CRANKCASE VENTILATION MEANS COMPRISING: CONDUIT MEANS CONNECTING SUCH CRANKCASE WITH SUCH INLET MANIFOLD; A CRANKCASE DEPRESSION REGULATOR IN SAID CONDUIT MEANS AND REGULATING THE FLOW OF CRANKCASE VAPORS FROM SUCH CRANKCASE TO SUCH INLET MANIFOLD; FRESH AIR INLET MEANS COMMUNICATING SUCH CRANKCASE WITH ATMOSPHERE; AND ONE-WAY VALVE MEANS IN SAID FRESH AIR INLET MEANS, SAID VALVE MEANS BEING OPERATIVE TO PREVENT THE ESCAPE OF CRANKCASE VAPORS TO ATMOSPHERE AND TO LIMIT THE FLOW OF FRESH AIR INTO SUCH CRANKCASE THROUGH SAID INLET MEANS, SAID ONE-WAY VALVE MEANS COMPRISING: PASSAGE MEANS PROVIDING FOR THE FLOW OF VENTILATING AIR THERETHROUGH; A FLEXIBLE REED SECURED TO SAID PASSAGE MEANS AND MOVABLE INTO AND OUT OF A POSITION BLOCKING THE FLOW OF AIR THROUGH SAID PASSAGE MEANS; AND STOP MEANS SPACED FROM SAID PASSAGE MEANS AND ADAPTED TO BE ENGAGED BY SAID REED WHEN OUT OF SUCH LOCKING POSITION TO MAINTAIN A DESIRED MAXIMUM CLEARANCE BETWEEN SAID REED AND SAID PASSAGE MEANS SO AS TO PROVIDE A PREDETERMINED RESISTANCE TO AIR FLOW THERETHROUGH INTO SUCH CRANKCASE. 